JPH01156931A - Separation of aromatic sulfonic acid from aqueous solution or suspension - Google Patents

Abstract

PURPOSE: To obtain the objective compd. from an org. phase by extracting an aq. soln. or aq. suspension containing aromatic sulfonic acid or its alkali salts by using an org. solvent not miscible with water selected from alcohols, ketones, carboxylic acid esters.

CONSTITUTION: An aq. soln. or aq. suspension containing aromatic sulfonic acid or its alkali salt (e.g. Na salt) is extracted with an org. solvent not miscible with water or slightly miscible with water. The org. phase is separated, and if necessary, radical aromatic sulfonic acid is converted into an alkali salt, and the org. solvent is removed to obtain the objective material. As the org. solvent, 4 to 8C alkanol is especially preferable, and especially isobutanol is excellent. The extraction is carried out by adding the org. solvent at 15 to 90°C for 5 to 30 min under stirring. The objective compd. can be separated in ≥95% yield by one extraction, but extraction by several times is advantageous. The obtd. material of the title is useful as a synthetic intermediate for dyes.

COPYRIGHT: (C)1989,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an aromatic sulfonic acid or an alkali salt thereof by extraction from an aqueous solution or suspension containing an aromatic sulfonic acid or an alkali salt thereof using an organic solvent that is immiscible or slightly miscible with water.
This invention relates to a method for separating aromatic sulfonic acids.

Since aromatic sulfonic acids generally have good water solubility, they can be obtained by separation of the corresponding aromatic compound from an aqueous solution or suspension and sulfonation with concentrated sulfuric acid or hydrochloric sulfuric acid, in which case the reaction is carried out after the completion of the reaction. The mixture is removed on ice and optionally neutralized with caustic soda solution. However, by conventional methods, i.e., the production of sodium sulfonate or betaine, it is generally not possible to quantitatively separate the desired sulfonic acid from the aqueous solution, which reduces the yield of the product and wastewater is It will become contaminated.

According to DE 21 39 477 A1, it is known to separate paraffin sulfonic acids from aqueous sulfonation mixtures, in which alcohols having at least 5 carbon atoms in the molecule are used as extractants. In this case, the components to be separated have good compatibility with the extractants used due to their long hydrophobic alkyl chains. However, their molecular structure is different from aromatic sulfonic acids, which are known to be polar, and especially aromatic sulfonic acids that are substituted with polar groups. was unthinkable.

This was thought to require a more polar solvent.

Specifically, FRA2532618 describes that sulfonated triarylphosphines are extracted from an aqueous phase using phosphoric acid, phosphonic acid, or phosphinic acid ester, phosphine, or oxide. However, these extractants are toxic and unsuitable for industrial use.

The object of the invention was to provide a method which overcomes the above-mentioned disadvantages in simple ways and which can be operated without the need for extra large equipment and security measures.

The present inventors prepared an aqueous solution or aqueous suspension containing an aromatic sulfonic acid or an alkali salt thereof using an organic solvent that is immiscible or slightly miscible with water selected from the group of alcohols, ketones or carboxylic acid esters. from an aqueous solution or aqueous suspension, by extraction using a solvent, separating the organic phase and optionally converting the free aromatic sulfonic acid contained therein into its alkali salt, and then removing the organic solvent. It has now been found that aromatic sulfonic acids can be advantageously separated in the form of free acids or alkali salts.

The aromatic sulfonic acids separated by the method of the invention are, for example, those derived from penzole. It usually has only one hydroxysulfonyl group. The benzene nucleus may have one to several substituents and/or may be benzo-fused.

Examples of suitable substituents include halogen atoms, hydroxyl groups, and the following groups. C, %C, -C rule, C1-C4-alkoxy, nitro, amino, CLA-C4-mono- or dialkylamino, pyrrolidino, piperidino, morpholino,
Piperazino, (N-C, ~C4-alkyl)-piperazino, C, ~C4-dialkylaminomethyl, 2- (C
1-C4-dialkylamino)-ethyl, (N-01-
C4-alkyl-N-phenylamino)-methyl, 2-
(N-C1-C4-alkyl-N-phenylamino)-
Ethyl (in the case of the latter two, the phenyl group present in the amino group may be further substituted, for example by a halogen atom, a C,%C4-alkyl group or a C,-C,-alkoxy group), 5-( C, ~C6-alkyl)-pyrazol-6-one-1-yl, 3-(C, ~C4-alkyl)
-pyrazol-5-one-1-yl or 2-[6- or 5-cyano- or -carbamoyl-4-(c, ~C4-
Alkyl]-6-valogenopyridin-1-ylaminoco-ethyl.

When the benzene ring is further benzo-fused, it is especially a naphthalene type, anthracene type or phenanthrene type. These polycyclic systems may have the substituents mentioned above. In the case of anthracene, anthraquinone is also included.

Examples include the following sulfonic acids.

O3H Alkaline salts are, for example, lithium salts, sodium salts or potassium salts, with sodium salts being preferred.

The extractant used in the present invention is an organic solvent selected from the group of alcohols, ketones or carboxylic acid esters, which is immiscible or slightly miscible with water. Examples include the following:

Alcohol: 04~Cl0-alkanol or HaC,~C
7-Cycloalkanols such as butanol, isobutanol, secondary butanol, pentanol, impentanol, secondary pentanol, hexanol, 2-ethylhexanol, cyclopentanol, cyclohexanol, 4-methylcyclohexanol or cycloheptatool .

Ketones: C4-C6-alkanones or C3-C7-cycloalkanones, such as methylethylketone, diethylketone, diimpropylketone, di-n-propylketone, methylimpentylketone, cyclopentanone, cyclohexanone or cycloheptanone.

Carboxylic acid esters: 01-C8-alkyl esters or cyclic esters of acetic acid, methoxyacetic acid or propionic acid, such as ethyl acetate, butyl acetate, ethyl methoxyacetate, ethyl propionate or γ-butyrolactone.

The process according to the invention is preferably carried out using alcohols, 04-C8-alkanones or carboxylic acid esters having a total of up to 10 carbon atoms as extractants. Especially 04~C6
-Preference is given to using alkanols, among which butanol, pentanol and especially imbutanol are preferred.

The method of the present invention is preferably carried out as follows. An organic solvent is added to an aqueous solution or suspension containing an aromatic sulfonic acid or an alkali salt thereof, and the mixture is heated at a temperature of 0 to 100°C, preferably 15 to 90°C, for 5 to 60 minutes, preferably 5 to 60°C.
Stir for 30 minutes. The phases are then separated and the organic phase (usually the lighter one) separated and subjected to conventional methods such as distillation (optionally under reduced pressure).
Or remove the organic solvent using a disk dryer. The desired product is obtained in this case in solid form in aqueous solution or as a suspension. The organic solvent can be recovered and reused for extraction.

In this method, the weight ratio of sulfonic acid (or its alkali salt) to organic solvent is, for example, about 1=1 to 1:5, preferably 1:1 to 1:3.

To avoid or reduce the loss of organic extractant, when using slightly water-soluble extractants such as inbutanol, it is possible to extract the suspension with an aqueous solution saturated with sodium chloride or thorium sulfate or with water. preferable. It is advantageous to extract the aqueous reaction mixture obtained in the work-up of the aromatic sulfonation reaction directly by the process of the invention.

If the sulfonic acid is easier to extract than the free acid in the form of an alkaline salt, particularly a sodium salt, the salt formation is carried out in an aqueous solution which is then subjected to extraction. However, it is also possible to carry out the salt formation directly after extraction of the free acid from the aqueous medium by adding the corresponding alkali hydroxide or carbonate in the organic phase.

In many cases, especially in the case of certain sodium sulfonates or free sulfonic acids (especially in the betaine form),
The formation of a suspension takes place in the organic phase. But this is not a hindrance. This is because in this case the organic phase is separated as a suspension from the aqueous phase and worked up in the customary manner.

A single extraction of the aqueous phase is generally sufficient to separate the aromatic sulfonic acid from the aqueous phase in a yield of 95% or more.

However, it is often advantageous to carry out several extractions.

The process of the invention can be operated both continuously and discontinuously and is used not only for the extraction of aromatic sulfonic acids from the reaction mixture (in its workup), but also for the extraction of aromatic sulfonic acids or their alkali salts in general. from aqueous solutions or suspensions.

The new method makes it possible to extract aromatic sulfonic acids or their alkali salts in a simple manner, and aromatic sulfonic acids and especially their alkali salts are present in high concentrations (approximately 50% % by weight).

The aromatic sulfonic acids separated by the method of the invention are valuable intermediates for the synthesis of dyes, for example.

In the formulas in the following examples, the structural element means a mixture of isomers, and in this isomer, those whose structures differ depending on the position of X exist as main components.

Example 1 A mixture of 190 g of compound A'-H and 81 g of compound A'-H is added to a mixture of 300 g of 96% by weight sulfuric acid and 500 g of 24% by weight oleum at 10-18 DEG C. while cooling with brine. After stirring at 15-17°C for 8 hours, the reaction mixture was mixed with 300 g of 50% by weight caustic soda solution.
and 1600 g of ice. Then add 500+++l of isobutyl/- to the mixture and add 35-5o0
After stirring at C for 15 minutes, the aqueous phase is separated and produced. 1
After 0 min, the inbutanol phase was separated and added with 94% caustic soda.
9 (50% by weight) and 3 g of sodium carbonate.

When evaporated to dryness in a disc dryer, a crystalline powder of 373.5
,! F (containing about 14.5 p of sodium sulfate as well as a total of 359 g of compounds A4-8o, Na and A''-SO3Na), the mixing ratio of which is unchanged from the raw material composition. Sulfonation product is expressed by the following equation.

The recovered inbutanol is
”-3o, H. The second extraction removes a small amount of remaining AI S○, H and A'-8○, H.
is quantitatively separated from the aqueous sulfuric acid phase.

Example 2 (N-ethyl-N-phenyl)-benzylamine 211
g of oleum (24% by weight) at a temperature below 20°C.
og and keep the temperature at about 70°C until the reaction is complete.
Rise. The mixture was then mixed with 1500 g of ice and 50% by weight.
Pour into 600 g of caustic soda solution and add inbutanol 101
Layer 00O. Next, 50% by weight caustic soda solution is added while stirring until the pH of the mixture becomes 7-11, and after stirring at 40-70° C. for about 10 minutes, the aqueous phase is separated. When the organic phase is dried in a disc type dryer, a colorless powder of the following formula is obtained with 306.5! 9, which is about -10
Contains crystallization water of I and traces of sodium sulfate.

The sulfonation reaction mixture was heated to 2000 ml of ice. ! 9(1soo)
) instead of y, the product is likewise obtained in satisfactory crystalline form.

An inbutanol solution of (N-ethyl-N-phenyl)-hensylamine-sulfonic acid Na salt can also be treated as follows.

a) The isobutanol is distilled off under atmospheric pressure at a temperature up to about 97° C., 150 mJ of water are added to the oily residue, and 100 ml of the water/inbutanol mixture are distilled off to give a water-dilutable solution of the desired product. is obtained. This solution can be used directly in the coupling reaction.

b) Alternatively, add 200 ml of water to the imbutanol-free concentrated solution obtained in (a), cool to 40°C, bring the pH to about 0.5-1 with sulfuric acid and concentrate the product. solution(
Coarse crystals in the form of betaine are precipitated from a total capacity of about 660 mA. This is suction filtered and dried.

The ratio is 94% of the theoretical value. By reusing the lachrymal fluid (after sulfonation but before precipitation), yields reach over 98%.

Example 3 2.4-Dichloroaniline 162I is dissolved in 200 g of 5% by weight oleum at room temperature. Mixture to degree 165-14
After rising to 0° C. and stirring for 4.5 hours, it is cooled to 80° C. and the reaction mixture is poured into a mixture of 1500 I of ice and 300 g of 50% by weight sodium hydroxide solution. The mixture obtained is extracted twice with 800 ml each of isobutanol as in Example 1. After the organic phases are combined and neutralized with sodium hydroxide solution and the inbutanol is evaporated off, the residue is steam distilled to remove unreacted starting materials. The residue is cooled to room temperature and the precipitated product of formula is filtered off with suction and dried to give 251y a colorless powder.

Example 4 (N-ethyl-N-phenyl)-benzylamine-3-
1 mol of sulfonic acid is prepared analogously to Example 2, but instead of inbutanol as extractant, n-butanol, methyl ethyl ketone, diethyl ketone, butyl acetate or cyclohexanone are used, respectively. (N
The sodium salt of -ethyl-N-phenyl)-benzylamine-3-sulfonic acid is extracted with similar yields and is obtained as a solid after removal of the respective solvent.

The products shown in Tables 1 to 6 below are also separated in the same manner as in the Examples. In Examples 6.7.12.13 and 27, the separation was not carried out within the scope of working up the reaction mixture, but from the respective aqueous solution or suspension, which was acidified by addition of sulfuric acid.

Table 1 Example number BI
B2b Rime No. 2 Table Example No. RI
R2o3H Instead of the cyanopyridines in Tables 1 and 2, the corresponding carbamoyl compounds can also be used.

Table 3 C1

Claims (1)

[Claims] 1. An organic sulfonic acid or an aqueous suspension containing an aromatic sulfonic acid or an alkali salt thereof that is not mixed or slightly mixed with water selected from the group of alcohols, ketones, or carboxylic acid esters. Aqueous solution or aqueous suspension, characterized in that extraction is carried out with a solvent, the organic phase is separated, optionally the free aromatic sulfonic acid contained therein is converted into its alkali salt, and then the organic solvent is removed. A method for separating aromatic sulfonic acids in the form of free acids or alkali salts from suspensions. 2. Process according to claim 1, characterized in that the extraction is carried out using alcohol as a solvent. 3. Process according to claim 1, characterized in that the extraction is carried out using a C_4-C_8-alkanol as solvent.